Mutations in the genes encoding isocitrate dehydrogenase, IDH1 and IDH2, have been reported in gliomas, myeloid leukemias, chondrosarcomas and thyroid cancer. We discovered IDH1 and IDH2 mutations in ...34 of 326 (10%) intrahepatic cholangiocarcinomas. Tumor with mutations in IDH1 or IDH2 had lower 5-hydroxymethylcytosine and higher 5-methylcytosine levels, as well as increased dimethylation of histone H3 lysine 79 (H3K79). Mutations in IDH1 or IDH2 were associated with longer overall survival (P=0.028) and were independently associated with a longer time to tumor recurrence after intrahepatic cholangiocarcinoma resection in multivariate analysis (P=0.021). IDH1 and IDH2 mutations were significantly associated with increased levels of p53 in intrahepatic cholangiocarcinomas, but no mutations in the p53 gene were found, suggesting that mutations in IDH1 and IDH2 may cause a stress that leads to p53 activation. We identified 2309 genes that were significantly hypermethylated in 19 cholangiocarcinomas with mutations in IDH1 or IDH2, compared with cholangiocarcinomas without these mutations. Hypermethylated CpG sites were significantly enriched in CpG shores and upstream of transcription start sites, suggesting a global regulation of transcriptional potential. Half of the hypermethylated genes overlapped with DNA hypermethylation in IDH1-mutant gliobastomas, suggesting the existence of a common set of genes whose expression may be affected by mutations in IDH1 or IDH2 in different types of tumors.
The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load, but its existing topology has a power ...limitation due to the wide range of discontinuous conduction mode during battery discharge. This paper proposes a new topology of the energy-stored qZSI to overcome this disadvantage. The operating characteristic of the proposed solution is analyzed in detail and compared to that of the existing topology. Two strategies are proposed with the related design principles to control the new energy-stored qZSI when applied to the PV power system. They can control the inverter output power, track the PV panel's maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. An experimental prototype is built to test the proposed circuit and the two discussed control methods. The obtained results verify the theoretical analysis and prove the effectiveness of the proposed control of the inverter's input and output powers and battery power regardless of the charging or discharging situation. A real PV panel is used in the grid-tie test of the proposed energy-stored qZSI, which demonstrates three operational modes suitable for application in the PV power system.
6061 Al-based composites reinforced with 10% volume fractions of 6.94μm SiC particles (SiCp) have been fabricated by powder thixoforming, and the effects of solution treatment on their tensile ...properties and strengthening mechanisms were investigated. The obtained results indicate that the addition of SiCp significantly improved the tensile strength of a 6061 Al matrix alloy, but reduced its ductility. The ultimate tensile and yield strengths of the alloy increased from 180MPa and 99MPa to 230MPa and 128MPa, respectively, while its elongation decreased from 8.0% to 2.6%. However, the solution treatment at 535°C for 6h significantly alleviated ductility losses and further enhanced the composite tensile strength; as a result, its ultimate tensile strength, yield strength, and elongation were increased by 19.6%, 65.2%, and 161.5% up to 275MPa, 212MPa, and 6.8%, respectively. Due to the presence of SiCp, the resulting composite solution rate was noticeably decreased compared to that of the matrix alloy. The relationship between the solution time and the composite yield strength was discussed theoretically by using a modified micromechanical model, which took into account the SiCp failure. The obtained theoretical results were in good agreement with the experimental ones.
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•A novel processing technology for composite, powder thixoforming is proposed.•Solution treatment can compensate ductility loss besides enhancing tensile strength.•Solid solution strengthening makes largest contribution and Orowan mechanism is minor.•The theoretical calculations are well consistent with the experimental values.
A novel in situ core–shell-structured Ti@(Al–Si–Ti) particulate-reinforced A356 composite was synthesized via powder thixoforming. It is noted that there is a significant improvement in toughness of ...the particulate-reinforced Al matrix composites, and the problems related to fabrication techniques were also solved. The effects of reheating duration at a semisolid temperature of 600 °C on the microstructure and tensile properties of the resulting composites were investigated. The results indicated that a thick, compact Al–Si–Ti intermetallic shell formed around the Ti powders when the reheating time was at 50 min. A composite containing these reinforcing particles exhibited good tensile properties. Its ultimate tensile strength and yield strength (YS) were decreased by only 2.1 and 3.5%, respectively, while its elongation was increased by 167.8% and up to 8.3%, compared to the (Al, Si)
3
Ti
p
/A356 composite that was thixoformed after the Ti powders had completely reacted. This occurred because the core–shell-structured particles with hard, compact shells exhibited strengthening role comparable to that provided by the monolithic (Al, Si)
3
Ti intermetallic particles, and the Ti core effectively inhibited or delayed crack propagation by blunting crack tips and severe plastic deformation. In addition, a modified shear lag model that incorporated the indirect strengthening mechanisms and varying shell thicknesses of Al–Si–Ti intermetallics was proposed to successfully predict the YS of the composites.
Highly biodiversity communities have been shown to better resist plant invasions through complementarity effects. Species richness (SR) is a widely used biodiversity metric but lacks explanatory ...power when there are only a few species. Communities with low SR can have a wide variety of phylogenetic diversities (PD), which might allow for a better prediction of invasibility.
We assessed the effect of diversity reduction of a wetland community assemblage typical of the Beijing area on biotic resistance to invasion of the exotic weed Alternanthera philoxeroides and compared the reduction in SR and PD in predicting community invasibility.
The eight studied resident species performed similarly when grown alone and when grown in eight‐species communities together with the invasive A. philoxeroides. Variation partitioning showed that PD contributed more to variation in both A. philoxeroides traits and community indicators than SR. All A. philoxeroides traits and community indicators, except for evenness index, showed a linear relationship with PD. However, only stem length of A. philoxeroides differed between the one‐ and two‐species treatments, and the diversity index of the communities differed between the one‐ and two‐species treatments and between the one‐ and four‐species treatments.
Our results showed that in natural or semi‐natural wetlands with relatively low SR, PD may be a better predictor of invasibility than SR. When designing management strategies for mitigating A. philoxeroides invasion, deliberately raising PD is expected to be more efficient than simply increasing species number.
In natural or semi‐natural wetlands with relatively low Species richness (SR), Phylogenetic diversities (PD) may be a better predictor of invasibility than Species richness (SR).
In this study, the effects of mold temperature on the microstructure and tensile properties of 2024 Al-based composites reinforced with SiC particles (SiCp; 10vol.%) and fabricated via powder ...thixoforming were investigated. The tensile properties of the composite were dependent upon the mold temperature because it affected the secondary solidification behavior, compactness of the secondary solidified structures, dislocation density introduced by the plastic deformation that occurs during thixoforming, and recrystallization behavior. The tensile properties of the composite that was thixoformed at 350°C exhibited the largest improvements, with the ultimate tensile strength (UTS) increasing by 235.4% (UTS=379MPa) and elongation decreasing by 31.0% (elongation=4.0%) compared to those of the as-cast 2024 alloy. The increased UTS was ascribed to the thermal-mismatch and load-transfer strengthening mechanisms, enhanced compactness, increased dislocation density, decreased grain size, and lower concentration of the deleterious θ-phase. The fracturing of the composites was caused by the cracking and debonding of the SiCp as the mold temperature increased, which in turn led to the total matrix failure.
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•Powder thixoforming technology exhibits superiority for fabricating SiCp/2024 composites.•Increasing mold temperature enhances compactness and deformation degree and decreases the concentration of θ-phase.•The best ultimate tensile strength of 379MPa is achieved at mold temperature of 350°C.•The cracking and debonding of the SiCp become predominant as the mold temperature increases.
•The impact responses and the energy absorptions of different density-graded cellular rods are investigated theoretically and numerically.•More than two shock fronts appear in the middle-low ...rod.•Suggestions are given for designing energy absorbing structure.
One-dimensional impact response of density-graded cellular rods with middle-low and middle-high density distributions is investigated theoretically and numerically. Analytical model based on shock-wave theory is proposed to predict impact response of density-graded cellular rods. The refined finite element calculations are performed using the periodic voronoi structures and agree well with the analytical predictions. It is found that there are two shock fronts in the density-graded rod with middle-high distribution while three shock fronts in the density-graded rod with middle-low distribution. Comparisons of the energy absorption capacity and the stress of the two ends of the rods show that the various gradient distributions may provide multiple selection schemes in the design of the prototypical multifunctional cellular systems.
Multilayer sandwich panel is a new potential lightweight structure in practical engineering applications. Dynamic response of fully clamped slender metal foam core multilayer sandwich beams struck by ...a low-velocity heavy mass is investigated. Based on the yield criteria for the multilayer metal sandwich cross-sections, analytical solutions and ‘bounds’ of analytical solutions for large deflection of the fully clamped slender sandwich beams are derived, in which interaction of bending and stretching induced by large deflections is considered. Numerical calculations are carried out and good agreement is achieved between the analytical solutions and numerical results. The dynamic solution approaches the quasi-static one when the mass ratio of the striker to the beam is large enough. Using the analytical formulae, optimal design charts are constructed to minimize the mass of multilayer sandwich beams for a given low-velocity impact resistance. It is shown that the dynamic and quasi-static solutions can capture the low-velocity heavy-mass impact response of fully clamped slender multilayer sandwich beams.
Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high catalytic efficiency. The usual immobilization of metal or metal oxide particles on ...semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited because of the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quantum dots with anchoring sites for single cobalt atoms in a defined Co–N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for the cobalt atom with high atom loadings up to 3.27 wt %. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separation, and reduced electrochemical impedance, while single Co atoms acted as the active site with strong oxidative ability. As a result, the photocatalysts showed excellent visible light-promoted photocatalytic efficiency with oxygen evolution rates up to 168 μmol h–1 g–1 via water oxidation, imine formation with high conversion (∼90%) and selectivity (>99%), and complete photodegradation of organic dyes.
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